The present invention relates to a pipe fitting for joining pipes made of elastic materials such as polyethylene or other plastic material.
Heretofore, various kinds of pipe fittings and methods for joining pipes made of elastic material have been developed. There are, for example; a packing type pipe fitting which presses a packing around the external periphery of a pipe joined to another by a pressing means, with no additional operation on the pipes to be joined; a pipe fitting in which an intrusion ring is made to intrude on the external surface of a pipe by a pressing means in order to prevent the slip out of a pipe in above-mentioned packing type pipe fitting; a method of joining by means of a bonding agent or adhesive; and a method of pipe fitting wherein pipes are joined by pressing a pipe to be joined together with another pipe. However, each of the above pipe fitting or methods has its own drawbacks in, for example, the air tight function of the pipes, maintenance of strength of pipes to be joined, facility at the pipe fitting operation, etc.
Particularly, in the pipe fitting where the pipe is joined by pressing the pipes to be joined, it has been impossible to maintain the initial compressed, deformed state for a long period of time after the pipes are fitted. For this reason, the latter method could not be used for laying gas pipes.